Intraoperative open chest epicardial high-density mapping and ablation for refractory ventricular tachycardia at time of magnetically levitated left ventricular assist device implantation

The patient was a 62-year-old woman with ischemic cardiomyopathy (left ventricular ejection fraction 15%), ventricular septal defect history postrepair, recurrent VAs with implantable cardioverter-defibrillator implantation, and 3 applications of endocardial ablation and stereotactic body radiation therapy (SBRT). Previous ablation and SBRT were all focused on the left infero-postero-lateral wall. One of the clinical electrocardiograms during ventricular tachycardia (VT) (Figure 1) was suggestive of epicardial exit (no inferior q wave, pseudo-delta wave 108 ms, and maximal deflection index 0.6). Percutaneous epicardial approach failed because of previous ventricular septal defect repair and SBRT with severe pericardial adhesion. Because of the patient's advanced heart failure, she was prepared for LVAD implantation. Two weeks before LVAD implantation, she had endocardial VT mapping and ablation, and would have intraoperative epicardial VT mapping and ablation during the LVAD implantation.

The patient was under general anesthesia and continuous transesophageal echocardiography monitoring during the whole procedure. After sternotomy, the cardiovascular surgeons dissected the pericardium and performed the pericardial adhesiolysis. Afterward, cardiopulmonary bypass was initiated. The EnSite Precision cardiac mapping system (Abbott Medical) was used in an impedance-only mode. Electrocardiogram leads and reference patches were placed in the modified position due to sternotomy (Figure 2, A). Warm lactate Ringer solution was pooled in the pericardial cavity. High-density electroanatomic maps were created by Advisor HDGrid Mapping Catheter (Figure 2, B) by the electrophysiologist (Video 1). Sinus voltage map revealed a low-voltage area over the left infero-postero-lateral area with local abnormal ventricular activation (LAVA) signals over the margin over the scar area (Figure 2, C), which was correlated with the isochronal late activation mapping of late potentials. LAVAs were defined as sharp high-frequency ventricular potentials that displayed fractionation or double or multiple components separated by very low amplitude signals. These signals were considered indicative of local electric activity arising from pathological tissue. Ventricular pacing from the patient's implantable cardioverter defibrillator at S1S2 400/300 ms induced monomorphic VT. Activation map showed a clockwise reentrant pattern around the scar area with LAVA signals (Figure 2, D, and Video 2), which was the site of isthmus. Ablation with the FlexAbility Ablation Catheter was performed with a power of 30 W/40 °C for 30 seconds of each point. During the ablation of the entry and exit site, VT was terminated. Rechecked sinus voltage map showed LAVA elimination.

The HeartMate III implantation procedure continued after ablation. The inflow cannula position was checked by pressing the left ventricular apex during transesophageal echocardiography visualization. Then, surgeons marked the center of the sewing ring, which was secured. The myocardium was removed using a coring device. Empirical circumferential endocardium ablation of the transitional zone surrounding the inflow cannula was performed to prevent the cannula adjacent VT. The HeartMate III was implanted. The total procedure time of electroanatomic mapping and ablation was 58 minutes. The surgical procedure was well tolerated.

There were 78 total treated VA episodes 5 months before LVAD implantation. Five-month follow-up after discharge from LVAD implantation, there were 31 episodes of treated VAs, more than a 50% reduction. Moreover, the documented recurrent VAs did not originate from the epicardium.

Meta-analysis of the VT in patients with an LVAD showed that scar-related reentry was the predominant mechanism of VT (90.3%) and that cannula-related VT was observed in 19.3% cases. Combined endo-epicardial scar ablation was associated with a significantly higher success rate. Epicardial VT ablation post-LVAD is limited because of difficult and unsafe percutaneous epicardial access, and VT recurrence rates after only endocardial ablation are between 24% and 38%. Therefore, epicardial VT ablation during the LVAD procedure is reasonable. Moss and colleagues reported the feasibility and utility of intraoperative epicardial scar mapping during LVAD implantation. However, the role of empirical intraoperative epicardial ablation to mitigate the risk of postimplant VT requires further study. Three case reports showed the feasibility of epicardial VT ablation during the LVAD procedure with favorable outcomes.^{,  ,}  Only 1 report discussed the empirical circumferential endocardium ablation of the transitional zone surrounding the inflow cannula, which used cryoablation of VT ablation.

This is the first case report in Asia describing intraoperative open chest epicardial high-density mapping and radiofrequency ablation, and empirical inflow cannula endocardial ablation during LVAD implantation. The procedure is feasible and might reduce the risk of post-LVAD VA.